Brake mechanism



March 25, 1941. l w, og JR 2,236,272

BRAKE MECHANISM Filed Oct. 31, 1939 2 Sheets-Sheet 1 INVENTOR JOHN w. LO GAN,\J a.

ATTORNEY March 25 1941.

.1, w. LOGAN, JR

BRAKE MECHANISM Filed Oct. 31, 19 39 2 Sheets-Sheet 2 a R M Ni Y mm? NO R W 0 mw m N w an ow W0. TO

mm 5 mwl 8 m3 we m9 m 0w 0 Patented Mar. 25, 1941 UNITED STATES,

PATENT OFFICE BRAKE MECHANISM Application October 31, 1939, Serial No. 302,141

14 Claims.

This invention relates to brakes for railway vehicles, and more particularly .to a multiple shoe brake mechanism embodying means responsive to braking torque for governing the degree of application of the brakes.

It has been proposed to pnovide brak equipments for railway trucks having clasp brake assemblies of more than the usual two brake shoes for each wheel, in order to obtain sufficient frictional br'ahing force to control th vehicle during operation thereof at high speed. In designing such a brake mechanism for certain classes of railway vehicle trucks, difilculty is sometimes experienced in providing adequate clearance between operating parts of the mechanism and the adjacent elements of the truck frame, and in the operation of a multiple shoe brake mechanism the several brake shoe elements may necessarily be mounted in such a manner as to result in undesirable operating conditions, such as unequal to ading of the brake shoes.

One object of my invention is to provide an improved truck brake mechanism of the type employing more than two brake shoe elements for each wheel, the operating pants of which are constructed and arranged to insure equalization of the forces with which the individual shoes are applied to the vehicle wheel or other rotating member, the assembled elements of the mechanism being adapted when mounted on the truck to provide adequate clearance with respect to structural members associated with the vehicle body.

Another object of the invention is to provide improved means for supporting a truck brake mechanism and for measuring the braking torque produced during an application of the brakes.

It is a further object of the invention to provide an improved multiple shoe brake mechanism of the above type having associated therewith means automatically operative to regulate the force with which the brake shoes are applied to the wheel and axle assembly in accordance with relative variations in a control pressure and in the braking torque produced.

Other objects and advantages of the invention will ice-apparent in the fiollo-wing more detailed description thereof, taken in conjunction with the accompanying drawings, wherein 5O ti-on of a railway truck having mounted thereon 'Fig. 1 is a diagrammatic plan view of a por-,

axle assembly indicated genemally by the character l I, on which the frame is supported through the medium of suitable journal boxes and truck springs, such as spring t3 shown Fig, 2 mounted on the vehicl truck is a brake mechanism including a pair of carrier frames 12 operatively suspended from the truck side frames 10 adj-acent the respective wheels each of which is adapted to support oppositely disposed pairs of brake heads and shoes M and I5.

. As is best shown in- Fi-g. 2, each carrier frame I2 is forged or otherwis formed as a flat member of irregular shape comprising a looped end portion l8 disposed at the side of the wheel adjacent the center of the truck, an arcuate middle portion t9 adapted to extend over the axle H, and a bar portion 20 adapted to project toward the end of the vehicl .truck. Each carrier frame I2 hung from the adjacent side frame member I0 of the vehicle truck through the medium of a linkage mechanism comprising a bellcna-nk lever 22 pivotally mounted on a pin 23 carried by the end l8 of the carrier frame [2, a similar bell crank lever 24 pivot/ally connected by means of a pin 25 to the bar portion 20 of the carrier frame, a pair of bell crank 1evers 21 and 28 openatively mounted on the side frame ID at opposite sides of the wheel II, and substantiaily vertically disposed hanger members 29 and 30, the first of which operatively sup ports the bell cmank lever 22 from the bell crank lever 21, while the other hanger member in like manner supponts the bell crank lever 24 from the bell crank lever 28.

As is shown in Fig. 1 of the drawings, each of the bell crank levers 21 is journaled on a pin 32 which is mounted on an inwardly extending bracket 33 carried by the adjacent side frame member I0,,the bell crank lever 21 being thus disposed in a plane parallel to that occupied by the associated carrier frame l2, which is in turn located at the inner side of the Wheel H. Simil=ar1y,'the bell crank lever 28 at each side of the vehicle truckis pivotal-1y mounted on a pin 35 which is carried by an inwardly extending bracket 36 formed on the side frame H), the bell crank lever 28 being in longitudinal alignment with the bell crank lever 21. 'It will be observed in Fig. 2 that the hanger member 29 is pivotally connected to an outwardly extending arm of the. bell crank lever 22 by means of a pin 50, and to a similarly disposed arm of the bell crank lever 21 bymeans of a pin 5| It will further be noted thatthe respective ends of the other hanger member are pivotally connected by pins 53 and 54 to outwardly extending arms of the bell crank levers 2'4 and 28.

The linkage mechanism operatively supporting each carrier frame l2 further includes a movable connecting rod 38, one end of which is pivotally connected by means of a pin 40 to an upwardly extending arm of the bell crank lever 22, and the opposit end of which rod is pivotally connected by means of a pin M to a downwardly extending arm of the bell crank lever 24, the bell crank levers being thus adapted for rotation in opposite directions about the respective pins 23 and 25 as the rod 38 is shifted from a normal position, for a purpose hereinafter explained. The rod 38 extends through the open ends -of a hollow spring casing 43, which is riveted or otherwise secured to the inner side of the looped portion I8 of the carrier frame i2, and which has mounted therein a coil spring l that is interposed between a pair of sleeve elements 35, each of which is slidably mounted in one end of the casing 43 and extends outwardly thereof. Flanges 45a are formed on the sleeve elements for engaging the respective end walls of casing 63. Collar elements 41 and 48 are secured to the rod 38 at opposite ends of spring casing 48, and are each adapted for engagement with the corresponding movable sleeve element 45 as shown in Fig. 2, so that movement of the rod 38 in either direction will be resisted by the coil spring 44, as hereinafter more fully explained. It should be understood that sufficient clearance space is provided between the rod 30 and the respective sleeve elements 45, and between the sleeve elements and the end portions of the spring casing 43, to permit slight angular adjustment of the rod with respect to the casing under operating conditions.

The two bell crank levers 21 and 28 carried by each side frame I of the truck are operatively connected together by means of a torque rod 51, one end of which is journaled on a pin 58 carried by an upwardly extending arm of the bell crank lever 2i, and the other end of which rod has a vertical slot 59 formed therein for receiving the upwardly extending arm of the bell crank lever 28. A stud 6i is carried by the arm of the bell crank lever 28 and engages in laterally disposed slots 52 formed in the end of the torque rod 51 for permitting relative movement of said elements as hereinafter set forth. The torque rod has a clevis portion 63 formed on the end thereof beyond the slot 59, which clevis portion is operatively connected with a torque control mechanism hereinafter described.

Each carrier frame I2 is adapted to support the brake shoes and heads I4 through the medium of laterally disposed pins 66, which are mounted in suitable bores formed in lug portions 61 of the carrier frame (see Fig. 1), which lug portions extend outwardly into the plane of the adjacent vehicle wheel, the brake shoes being thus adapted to be moved into engagement with the wheel tread. The other pair of brake shoes and heads I5 carried at the opposite side of each wheel II are pivotally connected by means of suitable pins 68 to the ends of a pair of levers 60, respectively, the other ends of which levers are journaled on a common pin I0 that is secured to a lug portion II formed on the carrier frame i2, as may be seen in Fig. 1. The levers 69 at each side of the truck are oppositely disposed within the plane of the adjacent wheel I5, and at angles substantially tangential with respect thereto, and are normally held in their release position, as illustrated, under the force of suitable biasing means, such as a tension spring 13 which may be connected to the upper of said levers and to a lug carried by the bar portion 20 of the corresponding carrier'frame.

Referring to Fig. 1 of the drawings, the two laterally spaced carrier frames I2 are adapted to be maintained 'in substantially parallel relation by suitable means such as a tie rod I5, the opposite ends of which are mounted in flexible rubber gripping elements 16 that are secured within suitable apertures formed in the respective carrier frames, the tie rods being adapted to permit slight relative play or movement of the carrier frame'in following the corresponding wheels as they move over irregularities in the rails, particularly during application of the brakes as hereinafter explained. Connecting the outer ends or bar portions 20 of the two carrier frames I2 is a brake cylinder beam I0, having rounded end portions 79, each of which is seated within a suitable socket formed in the bar portion 20 of each carrier frame I2, as shown in Fig. 1.

Centrally disposed with respect to the brake cylinder beam I8 and extending longitudinally of the truck frame is a brake cylinder device BI, the casing of which, as shown in Fig. 2, is provided with a clevis portion 82 adapted to be fitted over the brake cylinder beam I8 and pivotally connected thereto through the medium of a pin 83. A tie rod 85 is pivotally connected to a suitable lug portion 84 of the brake cylinder casing by means of a pin 86 and to a suitable lug 88 carried by one of the carrier frames I2 through the medium of a pin 8'! for maintaining the brake cylinder device BI against excessive movement out of normal alignment with the associated elements, while permitting relatively slight yielding of the connected parts during an application of the brakes while the vehicle is moving along the track. The brake cylinder device BI is of the usual type having a piston, not shown, which is responsive to an increase in the pressure of fluid applied thereto for operating a piston rod 89. The outer end of the piston rod 89 is formed as a clevis and is pivotally secured by means of a pin SI to the ends of a pair of pull rods 92, the outer ends of which are pivotally connected by means of pins 93 to brake beams 94, respectively, each of which is disposed transversely of the truck frame and is secured or formed integrally with the corresponding brake shoe pins 68 carrying brake shoes and heads I5.

Associated with the clasp brake apparatus already described is a torque responsive fluid pressure brake control equipment adapted for operation according to variation in the pressure of fluid in a control pipe for governing the supply and release of fluid under pressure to and from the brake cylinder device BI, which equipment is similar in some respects to that shown and described in my copending application filed in the United States Patent Office on March 23, 1939, Serial No. 263,591. As is best shown in Fig. 1 of the drawings, the torque control equipment includes a spring casing I00, an auxiliary spring casing IOI, a mechanically actuated control valve device I02, and a control cylinder device I03 adapted to respond to the variations in the pressure of fluid in a control pipe I04 extending throughout thetra-in, all of which devices are secured to the usual end piece I 06 by bolts or other suitable means.

The spring casings I00 and I0! are aligned transversely of the vehicle truck and have operatively mounted therein a thrust rod I01, the opposite ends of which extend outwardly beyond the respective spring casings. The outer end of the thrust rod I01 adjacent the spring casing'.ll00 is pivotally connected by means of a'pin I08 to one arm of a bell crank lever I09, which is journaled on a pin IIO carried by a bracket portion III formed on the end piece I06 of the truck frame. The other arm of the bell crank lever I09 is pivotally connected through the medium of the pin II2 to the clevis portion 63 of the adjacent torque rod 51, the bell crank lever being so disposed that movement of the torque rod 51 toward the center of the truck, or to the left as shown in Fig. 1, will efiect movement of the thrust rod I01 to carry pin I08 away from the spring casing I00, while movement of the torque rod 51 to the right will effect movement of the pin I08 toward the spring casing. The other end of the thrust rod I01 projecting beyond the spring casing IOI carries a pin II5 which forms a pivotal connection with a bell crank lever II6 that is journaled on a pin II1, which is in turn mounted on a bracket portion II9 of the truck frame. The other arm of the bell crank lever. H6 is pivotally connected by means of a pin I20 with the clevis portion I63 of the torque rod 51 on that side of the vehicle truck. It will be noted that the bell crank levers H6 and I09 are thus adapted to rotate together and in the same direction when the torque rods 51 are simultaneously actuated during an application of the brakes, as will hereinafter be explained.

A pair of spring seat elements I25 are loosely mounted within the openings in the ends of the spring casing I00 in sliding relation with the thrust rod I01, and have formed thereon annular collar portions I26 that are adapted for engagement with the end walls of the spring casing for limiting outward movement of the respective spring seat elements. Interposed between the spring seat elements I25 are a plurality of springs I21, which are adapted to resist inward movement of either element with respect to the spring casing I00. Slidably mounted on the thrust rod I01 and projecting above the end portion I06 of the truck frame is an arm I30, which engages and may be secured to the spring seat element I25 adjacent thereto, and which is adapted to be operatively engaged by a nut I32 carried by the thrust rod. At the opposite end of spring casing I00 a similar arm member I33 is slidably mounted on the thrust rod I01 in association with the adjacent spring seat element I25, which arm member is adapted to be operativelyv engaged by a nut I34 secured to the thrust rod. It will thus be apparent that if the thrust rod I01 is moved in one direction the nut I32 thereon will carry with it the associated arm I30 and spring seat I25 against the force of the springs I21 while the other arm I33 is held stationary, and if on the other hand the thrust rod is moved in the opposite direction the nut I34 will cause inward movement of the arm I33 and spring seat member I25 with respect to the spring casing while the arm I30 is held against movement.

Within the spring casing I0! is disposed a coil spring I 40 which is adapted to act against a collar portion I41 of a movable spring seat member I42, which is loosely mounted within the end opening of the spring casing and extends in sliding relation with the thrust rod I01 into operative engagement with a nut I43 carried by the thrust rod. The spring I40 is adapted to aid the springs I21 in resisting movement of the thrust rod I01 in response to clockwise rotation of the bell crank levers I09 and H6, as viewed in Fig. 1. When on the other hand the thrustrod' I 01 is moved in theopposite direction in response to counterclockwise turning of the bell crank levers I09 and I I6, the spring I40 is adapted to remain ineffective, so that only the springs I21 can resist such movement of the thrust rod. As will hereinafter more fully be explained, this arrangement of the springs I21 and I40 with respect to the thrust rod I01'is designed to permit application of a greater braking force on the wheel and axle assembly II when that assembly is leading, than the braking force applied to said wheel and axle assembly when it constitutes the rear or trailing wheel and axle assembly,

The control valve device I02 comprises a casing having a chamber I45, which communicates by way of a conduit I46 with the pressure chamber of the brake cylinder device 8I. The casing of the control valve device I02 also has formed therein an inlet valve chamber I48 communicating with a source of fluid under pressure, not shown, and containing an inlet valve element I49, that is adapted to be held in the normal seated position under the force of a spring I50. An exhaust valve element I52 is operatively mounted within an exhaust valve chamber I53, which is formed in the casing adjacent the chamber I48 and communicates by way of a pipe I54 with the atmosphere, and also by way of a communication controlled by the exhaust valve element with the chamber I45. A spring I56 is provided for urging the exhaust valve element I52 toward seated position. Within the chamber I45 is mounted a valve actuating mechanism comprising a lever I51 secured to a centrally disposed pin I50, which is journaled in the casing. One end of the lever I51 is adapted to engage a valve stem I59 connected through the exhaust valve element I52, and the other end thereof is similarly engageable with a valve stem I60 for operating the supply valve element I49.

Forming part of or secured to the pin I58 is an arm I63, which is disposed outwardly of the casing of the control valve device I02 and operatively engages a ring member I64 carried on the end of a Bowden wire I65. The Bowden wire I65 is of the usual construction and extends slidably through a flexible tube I66, one end of which tube is secured to an arm I68 aligned with the control cylinder device I03. The other end of the flexible tube I66 is secured to the outermost portion of the arm I30 associated with the spring casing I00, the arm I30 being suitably apertured to accommodate the adjacent portion of the Bowden wire I65, which in turn is secured to the other arm I33. As is shown in Fig. 1, the Bowden wire I65 and tube I66 are of suflicient length to provide the curvature thereof required for effecting movement of the Bowden wire in response to operation of the flexible tube, without interference with independent operation of the Bowden wire when the tube is held stationary.

.I'he free end of the arm I68 to which one end of the flexible tube I66 is secured is fastened by suitable means to the outer end of a piston rod I10, which is slidably mounted in the casing of the control cylinder device I03. The piston rod I is operative by a piston I'II, which is slidably mounted within the casing and is subject to the opposing pressures of a coil spring I 12 and of fluid in a chamber I14 communicating with the control pipe I04.

Operation When the brake mechanism is in release position, as illustrated in the drawings, the control pipe I04 is connected with the atmosphere through suitable communications in the usual rake valve device, not shown, and the spring H2 is thus permitted to maintain the piston III and rod I'm in the innermost position thereof. The arm I88 thereby positions the flexible tube I 66 and Bowden wire I65 for maintaining the control valve device I62 in release position, the arms I63 and lever I! being thus adapted to hold the release valve I52 away from its seat while permitting the spring I 50 to maintain supply valve I49 in seated position. With the control valve device I52 disposed in release position, the piston chamber of the brake cylinder device 8| is connected to the atmosphere by Way of the conduit I46, chamber I45 of the control valve device, valve chamber I53, and discharge pipe I54.

The usual release spring mounted within the brake cylinder device 8! and not shown in the drawings, together with release springs I3 acting on the individual brake lever assemblies, are thereby permitted to act through the medium of the pull rods 52 and other operative members on the brake assembly already described to maintain the pairs of brake shoes I5 and I4 at each side of the truck out of engagement with the wheels II. Both carrier frames I2 and the elements mounted thereon are thus adapted to assume normal free-hanging positions, with the entire weight of each supported through the medium of the hanger members 29 and 30, as shown in Fig. 2.

When it is desired to effect an application of the brakes, fluid under pressure is supplied in the usual manner to the control pipe I 04 to effect an increase in the fluid pressure therein corresponding with the desired degree of application of the brakes, and the pressure of fluid thus admitted to the piston chamber I14 moves the piston Ill and rod I outwardly against the force of spring I72. The arm IE8 is carried outwardly with the piston rod and moves the end of the tube I65 connected thereto, together with Bowden wire IE5, for effecting movement of the arm I53, lever I51 and pin I 58 in a clockwise direction, it being understood that both the Bowden wire and tube are thus adapted to be operated simultaneously since the opposite ends thereof connected to arms I30 and I33 are maintained against movement by the force of springs IZ'I. As the lever I5! is thus turned in a clockwise direction, the stem I59 is operated to permit movement of the release valve I52 into seated position, where it is maintained under the force of spring I55, while the stem I60 is operated to unseat the supply valve I49 against the force of spring I55. With the supply valve I49 in unseated position, fluid under pressure is quickly supplied from the usual source, not shown, by way of valve chamber I48, chamber I45, and conduit I 48 to the piston chamber of brake cylinder device 8|.

Upon the supply of fluid under pressure to the brake cylinder devicethe piston rod 89 is forced outwardly by operation of the usual piston, and acts through the medium of the pin 9I, pull rods 92, and beams 94 to draw the brake shoes I5 into engagement with the wheels II, as may best be understood by reference to Fig. 2. At substantially the same time, each brake carrier frame I2 is pulled to the right, as viewed in Fig. 2, under the reactive force exerted through the medium of the brake cylinder casing carried by the carrier frame, so that the other brake shoes I4 are brought into engagement with the tread of the wheel II. It will be readily understood that since the two pairs of brake shoes I4 and I5 are disposed in clasp arrangement with respect to each wheel II, the force exerted by operation of the brake cylinder device BI is distributed substantially equally among the four brake shoes regardless of the pressure of fluid supplied by the brake cylinder device.

It will be understood that the vertical distance between the axle II and the adjacent side frame II) of the vehicle truck, which is supported through the medium of the truck springs such as spring I3, will vary under different vehicle load conditions, and that while the axle is moving along the track the wheel and axle assembly is constantly subjected to vertical movement with respect to the truck frame due to various irregularities in the rails. The brake mechanism constructed in accordance with the invention is not, however, adversely effected by such vertical relative displacement of the wheels with respect to the frame, the carrier frames I2 and associated brake shoes being constructed and arranged to follow the associated wheel and axle assembly II during an application of the brakes Without interfering with the usual action of the truck springs I3.

Assuming, for example, that the Wheel II is spaced a greater distance from the side frame Ii] than is the case in Fig. 2 of the drawings, and that the brake shoes I4 and i5 are operated to clasp the wheel in braking relation therewith, it will be apparent that the carrier frame I2 is thereby pulled downwardly so that the bell crank lever 22 is turned in a clockwise direction about the pin 23 while bell crank lever 24 is turned in a counterclockwise direction about the pin 25, since the arms of the levers respectively secured to the pins 50 and 53 are anchored through the medium thereof to the side frame. In thus rotating the two bell crank levers shift the connecting rod 38 toward the right. as viewed in Fig. 2, against the opposing force of the spring 44, which is partly compressed through the medium of the collar 48 and the sleeve member 45.

On the other hand, if the wheel II is displaced upwardly with respect to the side frame IU of the truck shown in Fig. 2, the carrier frame I2 and associated elements are adapted to follow such movement, the bell crank lever 22 being in that case rotated in a counterclockwise direction about the pin 23 while the bell crank lever 24 is turned in a clockwise direction about the pin 25, so that the rod 38 is shifted to the left against the opposing pressure of the spring 44. It will be understood that each carrier frame I2 is thus operative to follow the adjacent wheel I i without interfering with similar action of the opposite carrier frame associated with the same wheel and axle assembly, because of the yieldable connection maintained between the two carrier frames through the medium of the connecting rods I5 and the pivotally mounted brake cylinder beam I8.

Meanwhile, with the brake shoes I4 and I5 in braking engagement with the wheels I I, the carrier frames I2 are subjected to braking torque corresponding to the force with which the shoes are applied to the wheels. Assuming that the wheel II shown in Fig. 2 is disposed at the leading end of the truck and is thus rotating in a clockwise direction, the torque transmitted to the carrier frame l2 through the medium of the brake shoes I4 and I5 tends to effect downward movementofthe bar portion 23 and upward movementof end portion I8. It willbe evident that as the carrier frame I2 is thus subjected'to braking torque, tending to tilt the frame in a clockwise direction with respect to the wheel and axle II, the position of the connecting rod 38 and bell crank levers 22 and 24 relative to the carrier frame is not altered, since the forces on those members are balanced, and that consequently the hanger member 36 is pulled downwardly while the other hanger member 29 is forced upwardly. The bell crank levers 21 and 26 carried by the side frame I6 are thereby partially turned about the respective pins 32 and 35 so as to shift the torque rod 57 to the right, as viewed in Fig. 2.

Referring to Fig. 1, it will be understood that the operation just explained is effective to move both torque arms 51 toward the adjacent end of the truck or to the right as viewed in the drawings, and that both bell crank levers I69 and I I6 are consequently rotated in a clockwise direction about the corresponding pins H6 and II! for shifting the thrust rod I61 in opposition to the combined forces of the springs I21 and I46, which springs resist movement of the spring seat members I25 and I M which are respectively engaged by nuts I32 and I43 and carried with the thrust rod. In so moving, the thrust rod I61 carries with it the arm member I36, which consequently exerts a pulling force on the flexible tube I66, while the other arm member I 33 and the adjacent end of the Bowden wire I65 attached thereto are maintained stationary due to engagement of the collar portion I26 of the associated spring seat member I25 with the end of the spring casing I66, As the flexible tube I66 is thus pulled,

it tends to straighten, and thereby ejects the outer end of the Bowden wire I65 carrying the ring member I64.

As the Bowden wire I65 is thus moved outwardly from the end of the hollow flexible tube I66 adjacent the control valve device I62, the ring I64 operates the arm I63 to turn the pin I58 and lever I51 in a counterclockwise direction until the supply valve member I49 is moved into engagement with its seat, thereby cutting off further supply of fluid under pressure to the brake cylinder device BI. The brakes are then maintained applied with the desired force as determined by the position in which the arm I68 and piston I'II of the control cylinder device I63 are maintained under the pressure of fluid established in the control pipe I64.

If the force with which the brake shoes engage the wheels should exceed the desired value as predetermined by the pressure of fluid in the control pipe I64 as just explained, the .resultant torque is accordingly increased 'so as to effect further displacement of the two torquerods 51 and consequent operation of the thrust rod I61 and Bowden wire I65 until the control valve device I62 is operated to release position. With the control valve device I62 in release position fluid under pressure is discharged from the brake cylinder device 8| by way of the conduit I46, chamber I45 and past the unseate'd' valve I52, thus initiating release of the brakes." .Uponpartial lessening in the force with which the brake and the associated elementsof thetorque meas uring mechanism toward their normal position.-

In moving the thrust rod I61 toward normal'riosition, the springs I 21 at the same time act through the medium :of the spri'ngseat member: I25 and arm I36Lto push the adjacent end of the flexible tube I66 away from the other arm I33 which is connected .to the Bowden wire I65, and as a result the remote end of the Bowden wire carrying the ring I64 is retracted for operating the arm I63, pin I58 and lever I51 in a clockwise direction until the discharge valve I52 is again moved into engagement with its seat. The control valve device I62 is then in lap position so that the brakes are still maintained applied with the desired force corresponding to the pressure of fluid in the control pipe I64.

When it isdesired to effect the release of the brakes thecontrol pipe I64 is connected with the atmosphere by the usual operation of the associated brake valve device, not shown, whereupon the spring I12 becomes effective to force the piston I II of the control cylinder device, together with the piston rod I16 and arm I68, to the normal position as shown in Fig. 1. As the arm I68 is thus returned to normal or release position the flexible tube I66 and Bowden wire I65 are operated to effect movement of the control valve device I62 to the release position, in which the supply valve I49 is 'held in engagement with its seat while the release valve I52 is unseated. The

consequently reduced-to that of the atmosphere,-

so that the piston and piston rod 89 thereof are permitted to return to release position under the force of the various release springs, including the springs I3 acting through the medium of the corresponding brake levers 69 and pull rods 92. In so moving to release position the levers 69 withdraw the brake shoes I5 from engagement with the Wheels II, while the carrier frames I2 and brake shoes I4 carried therebyassume their release positions, as illustrated in Fig. 2 of the drawings.

If the railway truck is traveling in the opposite direction from that assumed for the foregoing description of operation, so that the wheel and axle assembly II is disposed at the rear ortrailing portion of the truck andis rotating in a counterclockwise direction as viewed in Fig. 2, an application of the brake shoes to the wheels will effect operation of the torque control mechanism in substantially the same manner as has already been explained. In that case, however, the spring I46 carried within spring casing I6I is adapted to remain inoperative to oppose movement of the thrust rod I61 in response to braking torque, so that the control valve device I62 is consequently actuated to maintain higher brake cylinder pressure in proportion to braking torque than that produced with the brake apparatus for the leading wheel and axle assembly of the truck.

Assuming that an application of the brakes is effected while the wheel and axleassembly II is rotating in acounterclockwise direction as viewed in Fig. 2, and thus constitutes the trailing assembly of the truck, the braking torque exerted on the carrier frame I2 causes that member to tilt so that the bar portion 26 is raised slightly while the end portion I8 is forced downwardly. As

the bar portion 26 is forced upwardly this move- 29" so as to effect counterclockwise rotation of bell crank lever 21 about pin 32. The torque rod 51 is thereby shifted to the left, as viewed in Fig. 2, by the movement of the bell crank levers 21 and 23. Referring to Fig. 1 of the drawings, it will be understood that both torque rods 5'! are moved to the left at substantially the same time by the operation just explained, while the bell crank levers I 99 and I I 6 are both rotated in the counterclockwise direction for shifting the thrust rod It? from its normal position against the force of the springs I2'I, due to engagement of the nut I34 with the arm I33 and spring seat member I35. The spring I49, of course, remains inactive at this time since the thrust rod Ill! moves the nut I43 away from the spring seat member I42. Operation of the Bowden wire I65 and flexible tube I66 to actuate the control valve device I02 is then effected, in the manner hereinbefore explained, to control the degree of application of the brakes. It will be observed, however, that since spring I40 is not effective the degree of application of the brakes will be limited to a lower value than when the wheel and axle assembly is the leading unit of the truck. Consequently, the degree of wheel sliding is minimized.

It will thus be seen that a truck brake equipment constructed in accordance with my invention embodies means insuring equal brake shoe loading during an application of the brakes, and

provides a normal brake mounting structure which is adapted on the one hand to measure braking torque for effecting automatic regulation of the applied braking force, and on the other hand to permit independent adjustment of an individual brake mechanism to follow vertical motion of the adjacent wheel with respect to the spring carried truck frame.

Although a single embodiment of the invention has been described in detail, it should be understood that I do not intend to limit the scope of the invention to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A brake mechanism for a wheel of a railway truck of the class having a spring supported frame, comprising carrier means, a plurality of brake shoes mounted thereon for movement into braking relation with the wheel, hanger means operatively suspending said carrier means from said frame, and yielding means cooperative with said hanger means for permitting said carrier means and brake shoes to follow vertical movement of said wheel with respect to said truck frame during application of the brakes.

2. A brake mechanism for a wheel of a railway truck of the class having a spring supported frame, comprising braking means operable to apply frictional force to said Wheel and axle assembly, hanger means operatively suspending said braking means from said truck frame, and spring-biased linkage mechanism operatively connected to said hanger means for normally maintaining said braking means centered in braking alignment with said wheel and axle assembly, said linkage mechanism being yieldable during an application of the brakes to permit said braking means to follow relative vertical movement of said wheel and axle assembly with respect to said spring supported truck frame.

3. A brake mechanism for a wheel of a railway truck of the class having a spring supported frame, comprising carrier means, a plurality of br .ke shoes mounted thereon for movement into braking relation with the wheel, hanger means operatively suspending said carrier means from said frame, and yielding means operatively mounted on said carrier means and cooperative with said hanger means during an application of the brakes for causing said carrier means and said. brake shoes to follow relative vertical movement of said wheel with respect to said truck frame.

4. A brake mechanism for a wheel of a railway truck of the class having a spring supported frame, comprising carrier means, a plurality of brake shoes mounted thereon for movement into braking relation with the wheel, hanger means operatively suspending said carrier means from said frame, and linkage mechanism operatively connected to said carrier means and hanger means and effective during engagement of said shoes with the wheel to prevent locking of said wheel against free vertical movement thereof with relation to said spring supported truck frame.

5. A brake mechanism for a wheel of a railway truck of the class having a spring supported frame, comprising carrier means, a plurality of brake shoes mounted thereon for movement into braking relation with the wheel, hanger means operatively suspending said carrier means from said frame, spring means mounted on said carrier means, and linkage mechanism yieldingly centered by said spring means and operatively connected to said hanger means for operation. during engagement of said brake shoes with the wheel, to cause said carrier and shoe assembly to follow relative vertical movement of said wheel with respect to said spring supported truck frame.

6. A brake equipment for a wheel and axle assembly of a railway truck of the class having a spring supported frame, comprising a pair of longitudinally disposed brake carrier members, hanger means carried by the truck frame and adapted to support each of said carrier members adjacent a wheel of said assembly, a plurality of brake shoes movably mounted on each of said carrier members in braking relation with the respective wheels, transversely disposed connecting members yieldingly secured at the ends thereof to the two carrier members, and spring biased linkage mechanism operatively connecting each carrier member with the corresponding hanger means for causing said carrier member to follow vertical movement of the adjacent wheel relative to the truck frame, when the brakes are applied, without appreciable interference with the similar movement of the other carrier member.

7. A brake equipment for a wheel and axle assembly of a railway truck of the class having a spring supported frame, comprising a pair of longitudinally disposed brake carrier members, hanger means carried by the truck frame and adapted to support said carrier members adjacent the wheels of said assembly, a plurality of brake shoes movably mounted on each of said carrier members in braking relation with the respective wheels, spring-biased linkage mechanism operatively connecting each carrier mechanism with the corresponding hanger means for causing said carrier member to follow vertical movement of the adjacent wheel relative to the truck frame, and common actuating means operatively connected to both carrier members for simultaneously operating said two sets of brake shoes.

8. A brake equipment for a wheel'and axle assembly of a railway truck of the class having a spring supported frame, comprising a pair of longitudinally disposed brake carrier members, hanger means carried by the truck frame and adapted to support said carrier members adjacent the wheels of said assembly, a plurality of brake shoes movably mounted on each of said carrier members in braking relation with the respective wheels, spring-biased linkage mechanism operatively connecting each carrier mechanism with the corresponding hanger means for causing said carrier member to follow vertical movement of the adjacent wheel relative to the truck frame, a brake cylinder device interposed between and carried by said carrier members, and lever means operatively connecting said brake cylinder device with the brake shoes aligned with both of said wheels.

9. In a brake mechanism for a wheel of a railway truck having a spring supported frame, in combination, a brake carrier member, a plurality of braking shoes operatively mounted on said carrier member for movement into braking relation with said wheels, brake operating means therefor, a torque lever mechanism operatively mounted on said truck frame and adapted to support said carrier member and brake shoes, said torque lever mechanism being responsive to braking torque produced on application of said shoes to the wheel for effecting regulation of said brake operating means, and spring-biased lever means mounted on said carrier member and operative during application of said brake shoes to the wheel to render said carrier member freely adjustable to follow vertical displacement of said wheel relative to said truck frame while effecting operation of said torque lever mechanism.

10. In a brake mechanism for a wheel of a railway truck having a spring supported frame, in combination, a brake carrier member, a pair of brake shoes journaled thereon and operatively aligned with one peripheral side of said wheel, brake lever means pivotally connected to said carrier member and disposed substantially tangential of the wheel, a pair of brake shoes mounted on said brake lever means and operatively aligned with the other side of said wheel, fluid pressure operated brake cylinder means connected to said brake lever means and operative to cause said two pairs of brake shoes to clasp said wheel in braking relation therewith, and hanger means for yieldingly supporting said carrier member and the elements mounted thereon from the truck frame.

11. In a brake mechanism for a wheel of a railway truck having a spring supported frame, in combination, a brake carrier member, a pair of brake shoes journaled thereon and operatively aligned with one peripheral side of said wheel, brake lever means pivotally connected to said carrier member and disposed substantially tangential of the wheel, a pair of brake shoes mounted on said brake lever means and operatively aligned with the other side of said Wheel, fluid pressure operated brake cylinder means connected to said brake lever means and operative to cause said two pairs of brake shoes to clasp said wheel in braking relation therewith, torque responsive brake controlling valve means operative to efiect supply and release of fluid under pressure to and from the brake cylinder means,

and linkage mechanism operatively carried by the truck frame and supporting said carrier member and brake shoes for transmitting forces, resulting from braking torque produced during application of the brakes, to said torque responsive brake controlling valve means.

12. In a brake equipment for a railway truck having at least one wheel and axle assembly and a frame resiliently mounted thereon, in combination, a plurality of fluid pressure operated friction brake mechanisms adapted to be carried in braking relation with the wheels of said wheel and axle assembly, respectively, torque responsive brake controlling valve means for regulating operation of the brake mechanism of each wheel, individual torque lever devices for supporting each of said brake mechanisms from the truck frame and arranged to transmit braking torque therefrom to the associated brake controlling valve means regardless of the direction of the rotation of the wheel, and separate biasing means for each of said torque lever devices adapted to resist movement thereof out of a normal position with one predetermined force when the wheel and axle assembly is leading, and with a different opposing force when said assembly is trailing.

13. A brake mechanism for a wheel of a railway truck having a spring supported frame, comprising, in combination, friction brake means including a carrier member disposed longitudinally of the truck frame and parallel to said wheel, two bell crank levers arranged parallel to and journaled on opposite ends of said carrier member, a rod pivotally connecting oppositely disposed substantially vertical arms of said levers so that said levers can be turned in opposite directions only, spring means mounted on said carrier member for urging said rod toward a normal position and opposing longitudinal displacement of said rod in either direction, and hanger means mounted on said truck frame and pivotally secured to oppositely projecting longitudinal arms of said bell crank levers, whereby said rod and connected bell crank lovers are operative against the force of said spring means to permit said friction brake means to follow vertical displacement of said wheel relative to said truck frame.

14. A brake mechanism for a wheel of a railway truck having a spring supported frame,

comprising, in combination, friction brake means.

including a carrier member disposed longitudinally of the truck frame and Parallel to said wheel, brake control means responsive to braking torque for automatically governing operation of said friction brake means, two spaced bell crank levers journaled on said truck frame above and in coplanar alignment with said carrier member, said bell crank levers having arms normally disposed in substantially vertical alignment and other arms normally extending in opposite directions horizontally, a horizontally arranged torque rod pivotally connected to said vertical arms of the bell crank levers, hanger members supporting said carrier member and pivotally connected to said other arms of the bell crank levers, and means for transmitting torque force, resulting from application of the brakes, from said torque rod to said torque responsive brake controlling means.

JOHN w. LOGAN, JR. 

